Add custom format functions for field output to prettytable (For example to format date/datetime) about prettytable

[BeldrothTheGold]

Please can you have a look at PR #136 and see if it would address your needs?

Yes, looks great. Thanks!

[BeldrothTheGold]

I was thinking it might be useful to add something more high level than specifically adding support for datetime format strings.

Something like adding a custom format function or ToString function to a field. Something that prettytable would call for each value in a column when generating the format string.

Something like this:

table.format_func["FieldName"] = lambda x: x.strftime("%Y-%m-%d %H:%M GMT")

[hugovk]

Please can you have a look at PR #136 and see if it would address your needs?